syzbot

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BUG: KASAN: use-after-free in perf_output_read_group kernel/events/core.c:5883 [inline]
BUG: KASAN: use-after-free in perf_output_read+0xee6/0x1050 kernel/events/core.c:5918
Read of size 8 at addr ffff8881d3b98a60 by task syz-executor436/16526

CPU: 1 PID: 16526 Comm: syz-executor436 Not tainted 4.14.155-syzkaller #0
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0xe5/0x154 lib/dump_stack.c:58
 print_address_description+0x60/0x226 mm/kasan/report.c:187
 __kasan_report.cold+0x1a/0x41 mm/kasan/report.c:316
 perf_output_read_group kernel/events/core.c:5883 [inline]
 perf_output_read+0xee6/0x1050 kernel/events/core.c:5918
 perf_output_sample+0xcea/0x1700 kernel/events/core.c:5960
 __perf_event_output kernel/events/core.c:6270 [inline]
 perf_event_output_backward+0x10b/0x220 kernel/events/core.c:6291
 __perf_event_overflow+0x12d/0x340 kernel/events/core.c:7541
 perf_swevent_overflow+0x7a/0xf0 kernel/events/core.c:7617
 perf_swevent_event+0x19c/0x270 kernel/events/core.c:7650
 do_perf_sw_event kernel/events/core.c:7758 [inline]
 ___perf_sw_event+0x2a4/0x4a0 kernel/events/core.c:7789
 __perf_sw_event+0x42/0x80 kernel/events/core.c:7801
 perf_sw_event include/linux/perf_event.h:1051 [inline]
 __do_page_fault+0x7b8/0xbb0 arch/x86/mm/fault.c:1461
 page_fault+0x42/0x50 arch/x86/entry/entry_64.S:1122
RIP: 4af788:0x4af6f8
RSP: 6dcc68:00000000006dcc60 EFLAGS: 006dcc6c

Allocated by task 9982:
 save_stack mm/kasan/common.c:76 [inline]
 set_track mm/kasan/common.c:85 [inline]
 __kasan_kmalloc.part.0+0x53/0xc0 mm/kasan/common.c:501
 kmalloc include/linux/slab.h:493 [inline]
 kzalloc include/linux/slab.h:661 [inline]
 rb_alloc+0x7b/0x4a0 kernel/events/ring_buffer.c:750
 perf_mmap+0xcc1/0x1480 kernel/events/core.c:5468
 call_mmap include/linux/fs.h:1803 [inline]
 mmap_region+0x7d9/0xfb0 mm/mmap.c:1736
 do_mmap+0x548/0xb80 mm/mmap.c:1512
 do_mmap_pgoff include/linux/mm.h:2215 [inline]
 vm_mmap_pgoff+0x177/0x1c0 mm/util.c:333
 SYSC_mmap_pgoff mm/mmap.c:1564 [inline]
 SyS_mmap_pgoff+0xf4/0x1b0 mm/mmap.c:1520
 do_syscall_64+0x19b/0x520 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
 0xffffffffffffffff

Freed by task 10013:
 save_stack mm/kasan/common.c:76 [inline]
 set_track mm/kasan/common.c:85 [inline]
 __kasan_slab_free+0x164/0x210 mm/kasan/common.c:463
 slab_free_hook mm/slub.c:1407 [inline]
 slab_free_freelist_hook mm/slub.c:1458 [inline]
 slab_free mm/slub.c:3039 [inline]
 kfree+0x108/0x3a0 mm/slub.c:3976
 __rcu_reclaim kernel/rcu/rcu.h:195 [inline]
 rcu_do_batch kernel/rcu/tree.c:2699 [inline]
 invoke_rcu_callbacks kernel/rcu/tree.c:2962 [inline]
 __rcu_process_callbacks kernel/rcu/tree.c:2929 [inline]
 rcu_process_callbacks+0x59f/0xf60 kernel/rcu/tree.c:2946
 __do_softirq+0x234/0x9ec kernel/softirq.c:288

The buggy address belongs to the object at ffff8881d3b98a00
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 96 bytes inside of
 512-byte region [ffff8881d3b98a00, ffff8881d3b98c00)
The buggy address belongs to the page:
page:ffffea00074ee600 count:1 mapcount:0 mapping:          (null) index:0x0 compound_mapcount: 0
flags: 0x4000000000010200(slab|head)
raw: 4000000000010200 0000000000000000 0000000000000000 00000001800c000c
raw: ffffea0007438880 0000000700000007 ffff8881da802c00 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8881d3b98900: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8881d3b98980: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8881d3b98a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                       ^
 ffff8881d3b98a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8881d3b98b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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